I got lucky and picked up a second hand HP-7475A for $50 about five years ago. It's the GPIB version, not native RS-232, so I also had to find a way to connect it to a modern PC. Ended up going with a GPIB<->USB adapter from AliExpress (about 10x cheaper than one from Prologix) to plug it into an RPi, which I can use to send HPGL files to get plotted.
Also got a friend to hack away a chunk of the plastic casing with a circular saw so I could use pen adapters for modern Sharpie and Stabilo markers, which are much easier and cheaper to acquire than old format plotter pens.
Quantising the oscillator pitch into discrete steps like this is pretty common when it comes to synthesisers. Generally there is also a fine-tuning control that allows the user to offset the output by up to an octave. Makes it easier to not be out-of-tune with other instruments.
About a year ago I stayed in a hotel and the door lock started misbehaving one morning while I was at breakfast. Went to the front desk, got a new card, went back to the room and discovered it still didn't work. After doing that two more times, someone was sent up to the room with a mysterious, palm-sized device with a USB cable hanging off it, which they plugged into a well hidden USB port on the bottom of the lock. The device performed some black magic, and after about 30 seconds a light on the lock changed colour from orange to red and it started functioning correctly again.
I use `ts` quite often in adhoc logging/monitoring contexts. Because it uses strftime() under the hood, it has automatic support for '%F' and '%T', which are much easier to type than '%Y-%m-%d' and '%H:%M:%S'. Plus, it also has support for high-resolution times via '%.T', '%.s', and '%.S':
Also got a friend to hack away a chunk of the plastic casing with a circular saw so I could use pen adapters for modern Sharpie and Stabilo markers, which are much easier and cheaper to acquire than old format plotter pens.